// 传入一个拖动的dragEl和一个目标targetEl，拖动dragEl去更新targetEl位置
export function useDraggable(targetEl, dragEl, options = { overflow: false }) {
  let transform = {
    offsetX: 0,
    offsetY: 0
  }
  const { overflow } = options

  const onMousedown = (e) => {
    const downX = e.clientX
    const downY = e.clientY
    const { offsetX, offsetY } = transform

    const targetRect = targetEl.getBoundingClientRect()
    const targetLeft = targetRect.left
    const targetTop = targetRect.top
    const targetWidth = targetRect.width
    const targetHeight = targetRect.height

    const clientWidth = document.documentElement.clientWidth
    const clientHeight = document.documentElement.clientHeight

    const minLeft = -targetLeft + offsetX
    const minTop = -targetTop + offsetY
    const maxLeft = clientWidth - targetLeft - targetWidth + offsetX
    const maxTop = clientHeight - targetTop - targetHeight + offsetY

    const onMousemove = (e) => {
      let moveX = offsetX + e.clientX - downX
      let moveY = offsetY + e.clientY - downY

      if (!overflow) {
        moveX = Math.min(Math.max(moveX, minLeft), maxLeft)
        moveY = Math.min(Math.max(moveY, minTop), maxTop)
      }

      transform = {
        offsetX: moveX,
        offsetY: moveY
      }

      if (targetEl) {
        targetEl.style.transform = `translate(${moveX}px, ${moveY}px)`
      }
    }

    const onMouseup = () => {
      console.log('drag on mouse up')
      document.removeEventListener('mousemove', onMousemove)
      document.removeEventListener('mouseup', onMouseup)
    }

    document.addEventListener('mousemove', onMousemove)
    document.addEventListener('mouseup', onMouseup)
  }

  const onDraggable = () => {
    if (dragEl && targetEl) {
      dragEl.addEventListener('mousedown', onMousedown)
    }
  }

  const offDraggable = () => {
    if (dragEl && targetEl) {
      dragEl.removeEventListener('mousedown', onMousedown)
    }
  }

  const resetPosition = () => {
    transform = {
      offsetX: 0,
      offsetY: 0
    }
    if (targetEl) {
      targetEl.style.transform = 'none'
    }
  }

  return {
    onDraggable,
    offDraggable,
    resetPosition
  }
}
